1. Field of the Invention
The present invention generally relates to depth of cut control for saws, and in particular to depth of cut control for concrete saws.
2. Background Information
Concrete saws are used to cut grooves in concrete surfaces so as to control the cracking which inevitably occurs as the concrete cures or hardens. They are used to cut grooves to form a fracture line in the surface of the concrete such that if and when the concrete does crack, it will crack along the cut line. This is done to prevent heaving and irregular surfaces which would inevitably occur otherwise.
The typical concrete saw is a self-propelled unit which has a main power engine which is used to drive a rotary, diamond-tipped saw blade, and an electrically driven hydraulic system which is used to raise and lower the saw.
The typical concrete saw has a mainframe and a set of rear drive wheels which are affixed to the mainframe and can be driven at a selectable speed. Attached to the mainframe is a sub frame with a second set of wheels, which is movable, normally by means of an independent hydraulic system to raise and lower the front of the concrete saw and the saw blade. This is done so that the saw blade can be elevated above the surface either for repair or replacement of the blade, or to move the saw from one location to another. The sub frame is then lowered down until the saw blade engages the concrete, and starts to cut into it. The operator can then continue to lower the blade as it cuts into the concrete to a selected depth of cut.
In selecting the depth of cut, there are a number of variables which include the diameter of the saw blade being used, depth of the concrete, the speed at which the blade is turning, and the drive speed at which the concrete saw is advanced along the line of cut. In general, the thicker the concrete surface the deeper the cut should be, yet the cut should not be so deep as to ensure complete fracturing along the cut line which subjects the concrete surface to inevitable fracture, and the possibility of heaving such as that induced by freezing of the subsurface and inevitable thawing during the change of seasons.
While devising a method of measuring the depth of cut might seem to be a simple matter, it is not in that depth of cut has to be calibrated for bearing diameters of the saw blades that are used on a concrete saw. And, for the topography, for example whether or not the cut is vertical on an inclined concrete surface such as those encountered on roads, sidewalks and driveways.
Accordingly, it is the object of this invention to provide a depth of cut apparatus which is adjustable in that it can be easily recalibrated for varying conditions and sizes of saw blades, and also will automatically stop at a preselected depth of cut when the saw is lowered the concrete surface being cut.
The present invention is an apparatus/method for use with concrete saws (or other cutting devices which have elevationally adjustable means for cutting grooves, slots, or trenches in the surface of a material at a selectable depth of cut). The invented apparatus automatically resets the depth of cut after the elevation of the saw or other cutting device has been changed from a selected depth of cut to another depth or elevation. One embodiment of the invented apparatus is utilized with a concrete saw having a rotating saw attached to elevationally adjustable means which is movably attached to a frame. The invented apparatus having a means for determining the elevation of the saw blade, relative to the surface of the material to be cut attached to the elevation means. The invented apparatus further having a means for identifying the elevation of the saw or other cutting device, relative to the surface of the material being cut, when the saw or other cutting device is cutting at a preselected depth of cut. The invented apparatus further having a means for automatically stopping elevational movement of the saw or other cutting device at the elevation of the preselected depth of cut when the elevation of the saw or other cutting device is adjusted to return it to the preselected depth of cut.
Still other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description wherein I have shown and described only the preferred embodiment of the invention, simply by way of illustration of the best mode contemplated by carrying out my invention. As will be realized, the invention is capable of modification in various obvious respects all without departing from the invention. Accordingly, the drawings and description of the preferred embodiment are to be regarded as illustrative in nature, and not as restrictive.